The present invention relates to an electronic endoscope provided with an endoscope unit having a solid-state imaging element, and a signal processing unit for processing an image signal output by the solid-state imaging element.
An electronic endoscope system is generally provided with an endoscope unit which has a CCD (Charge Coupled Device) at a distal end of an insertion portion thereof for capturing image of an object to be observed. The electronic endoscope system is further provided with an image signal processing unit which processes an image signal output by the CCD to generate a video signal. The video signal is transmitted to a displaying device such as a CRT (Cathode Ray Tube) display or the like, and/or to auxiliary devices (peripheral devices). Conventionally, electronic endoscope systems output analog video signals such as an analog RGB signal, analog composite signal, analog S-video signal and the like.
Recently, the peripheral devices (including displaying devices) provided with digital video signal input terminals have become developed and used. Using such devices is advantageous since the digital video signal has less deterioration due to attenuation of transmitted signal and is free from noise.
Image formed by the video signal output by the electronic endoscope system may be observed not only by an operator of the endoscope but also by an assistance, and/or many other people. For example, the image may be displayed on a displaying device located at a place or room remote from the electronic endoscope system. For this purpose, there has been desired that the peripheral devices utilizing digital video signal, which is not easily deteriorated.
It may be possible to convert the analog video signal once output by the conventional electronic endoscope into the digital video signal using an Analog to Digital (A/D) converter, and transmit the same to a peripheral device using the digital video signal. In such a method, however, the analog signal is once output, and then it is converted into the digital signal. Therefore, deterioration of the signal is unavoidable.
Further, a converting device for converting the analog signal to the digital signal should be additionally used together with the conventional electronic endoscope system, the number of cables for transmitting signals increased. Furthermore, the configuration of the endoscope system, operation thereof are complicated since the number of devices to be operated increases. Still further, a room for accommodating such a converting device should also become necessary. Therefore, using the A/D conversion together with the conventional electronic endoscope outputting the analog image signals is not practical.
Further to the above, various formats of digital video signals have been known. If there are plurality of peripheral devices which use digital video signals having different formats, a plurality of converting devices respectively corresponding to the formats of the video signals used by the plurality of peripheral devices should be employed in the electronic endoscope system.